1. Field of the Invention
The present invention relates to pyrenylamine derivatives having an unsaturated bond, which are useful as organic photoconductive materials for use in electrophotographic photoconductors and fluorescent whitening agents, aldehyde compounds serving as intermediates for producing the pyrenylamine derivatives, and methods for preparing the aldehyde compounds and the pyrenylamine derivatives.
2. Discussion of Background
Conventionally, many organic photoconductive materials for use in an electrophotographic process have been proposed. For example, there are known photoconductors comprising poly-N-vinylcarbazole or a triphenylamine compound as disclosed in U.S. Pat. No. 3,180,730; photoconductors comprising benzidine compounds as disclosed in U.S. Pat. No. 3,265,496, Japanese Patent Publication 39-11546, and Japanese Laid-Open Patent Application 53-27033; and photoconductors comprising stilbene compounds as disclosed in Japanese Laid-Open Patent Applications 58-198425, 58-198043, 58-189145, and 58-190953.
The above-mentioned electrophotographic process is one of an image forming processes, through which the surface of a photoconductor is charged in the dark by corona charges or the like. The charged photoconductor is exposed to a light image to selectively dissipate the electrical charges from the exposed areas, so that a latent electrostatic image is formed on the photoconductor. Furthermore, the thus formed latent electrostatic image is developed by a developer such as toner to a visible image.
Fundamental characteristics required for the photoconductor for use in such an electrophotographic process are: (1) chargeability to an appropriate potential in the dark, (2) minimum dissipation of electrical charge in the dark, and (3) quick dissipation of electrical charge when exposed to light.
However, the conventionally organic photoconductive materials have not satisfied the above-mentioned requirements (1) to (3) completely in practice.
On the other hand, inorganic materials such as selenium and zinc oxide are known as photoconductive materials for use in electrophotographic photoconductors. In particular, selenium photoconductors are widely used in practice. From the viewpoint of the recent electrophotographic process, in addition to various requirements for the electrophotographic photoconductors such as the above-mentioned fundamental characteristics, for instance, electrophotographic photoconductors have been required to be in the form of a belt with high flexibility. However, in the case of the selenium photoconductor, it is difficult to work them into the form of a belt.
To eliminate the shortcomings of the inorganic materials, various electrophotographic photoconductors employing organic materials have been proposed recently and some are put to practical use. Examples of the electrophotographic photoconductors employing organic materials are photoconductors comprising stilbene derivatives as disclosed in Japanese Laid-Open Patent Applications 58-198425 and 58-189145; and photoconductors comprising triarylamine derivatives as disclosed in Japanese Laid-Open Patent Application 58-65440. However, these photoconductors are still unsatisfactory for use in electrophotography.